style: trim verbose comments in _sanitize_messages

nanobot/providers/litellm_provider.py

@@ -12,9 +12,7 @@ from nanobot.providers.base import LLMProvider, LLMResponse, ToolCallRequest
 from nanobot.providers.registry import find_by_model, find_gateway
 
 
-# Keys that are part of the OpenAI chat-completion message schema.
+# Standard OpenAI chat-completion message keys; extras (e.g. reasoning_content) are stripped for strict providers.
-# Anything else (e.g. reasoning_content, timestamp) is stripped before sending
-# to avoid "Unrecognized chat message" errors from strict providers like StepFun.
 _ALLOWED_MSG_KEYS = frozenset({"role", "content", "tool_calls", "tool_call_id", "name"})
 
 
@@ -155,13 +153,7 @@ class LiteLLMProvider(LLMProvider):
     
     @staticmethod
     def _sanitize_messages(messages: list[dict[str, Any]]) -> list[dict[str, Any]]:
-        """Strip non-standard keys from messages for strict providers.
+        """Strip non-standard keys and ensure assistant messages have a content key."""
-
-        Some providers (e.g. StepFun via OpenRouter) reject messages that
-        contain extra keys like ``reasoning_content``. This method keeps
-        only the keys defined in the OpenAI chat-completion schema and
-        ensures every assistant message has a ``content`` key.
-        """
         sanitized = []
         for msg in messages:
             clean = {k: v for k, v in msg.items() if k in _ALLOWED_MSG_KEYS}